I'm facing an serious issue where data from one record is copied to another record (Overlay). I'm using MQ request for communicating to Mainframe systems using my C# code. we are facing issue which is very random/rarer where sending update request to Mainframe for one record copy information of another record previously processed by that thread. I'm using below code Background worker approach to create multi-threading on my servers.
My Question here is : Can objects created by one worker being used by another work ? is that possible ? this may be one of reason of overlay data.
Please help with you suggestion !!
BackgroundWorker worker;
worker = new BackgroundWorker();
worker.DoWork += new DoWorkEventHandler(DoWork);
worker.ProgressChanged += new ProgressChangedEventHandler(ProgressChanged);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(RunWorkerCompleted);
worker.WorkerReportsProgress = true;
worker.RunWorkerAsync();
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
backgroundWorker1.RunWorkerAsync();
}
struct SOmeData { }
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
SOmeData data = new SOmeData();
// backgroundWorker1 result
e.Result = data;
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// backgroundWorker1 result
SOmeData data = (SOmeData)e.Result;
// start backgroundWorker2
backgroundWorker2.RunWorkerAsync(data);
}
private void backgroundWorker2_DoWork(object sender, DoWorkEventArgs e)
{
// backgroundWorker1 result
SOmeData data = (SOmeData)e.Argument;
}
}
Related
Unfortunately I was not able to find relevant answer to my problem. I have a object encoder that has an event "VideoEncoding". It passes custom EncodingEventArgs that include various Properties like Progress, Size etc. I can output this info to Console or write to text file. But when I try to utilize it in WinForms I'm not able to pass that information to UI like label or progress bar. I tried different approaches. Background Worker seems like a good idea, The problem is that Background Worker cannot subscribe to VideoEncoding event, neither it will take my custom EventArgs. This is what i was able to put together. Maybe there is a different way to do it using delegates that would communicate with UI. Any suggestions are welcome. Thank you.
public partial class Form1 : Form
{
private BackgroundWorker bw;
int _progress;
public Form1()
{
InitializeComponent();
this.bw = new BackgroundWorker();
this.bw.DoWork += new DoWorkEventHandler(bw_DoWork);
this.bw.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged);
this.bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
this.bw.WorkerReportsProgress = true;
this.button1.Click += new EventHandler(button1_Click);
}
private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
this.label1.Text = "The job is: " + e.Result.ToString();
this.button1.Enabled = true;
}
private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
this.label2.Text = e.ProgressPercentage.ToString() + "% complete";
}
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = (BackgroundWorker)sender;
this.Encode
worker.ReportProgress(_progress);
e.Result = "Completed";
}
private void button1_Click(object sender, EventArgs e)
{
if (!this.bw.IsBusy)
{
this.bw.RunWorkerAsync();
this.button1.Enabled = false;
}
}
public void Encode()
{
var job = new EncodingJob();
//setup encoding job
//subscribe to an event
ffmpeg.VideoEncoding += GetProgress;
ffmpeg.DoWork(job);
}
public void GetProgress(object sender, EncodingEventArgs e)
{
_progress = (int)e.Progress;
}
}
Try to call the background workers ReportProgress in the GetProgress Method. How should the form know your progress if you don't signalize it?
I've looked in many places for this but still haven't found a solution. What I'm trying to achieve is being able to use BackgroundWorker on a timed basis. Here's an example:
public Main()
{
isDbAvail = new BackgroundWorker();
isDbAvail.DoWork += isOnline;
isDbAvail.RunWorkerCompleted += rewriteOnlineStatus;
}
private void rewriteOnlineStatus(object sender, RunWorkerCompletedEventArgs e)
{
Subs.Connection connection = new Subs.Connection();
changeStatus(connection.isDbAvail());
}
private void isOnline(object sender, DoWorkEventArgs e)
{
while (true)
{
Console.WriteLine("Checking database connection");
System.Threading.Thread.Sleep(8000);
}
}
public void changeStatus(bool status)
{
if (status)
{
serverStatusVal.Text = "Connected";
serverStatusVal.ForeColor = System.Drawing.Color.DarkGreen;
}
else
{
serverStatusVal.Text = "Not connected";
serverStatusVal.ForeColor = System.Drawing.Color.Red;
}
}
What's happening here is that the isOnline method checks if there is a connection to the database (just an example) every 8 seconds and changes the text accordingly. What I've noticed though, is that the while loop inside the isOnline method causes the rewriteOnlineStatus method never to fire because it runs indefinitely. Is there another workaround to this?
I suggest you use BackgroundWorker.ReportProgress, and check connectivity in the background thread.
Something like this:
public Main()
{
isDbAvail = new BackgroundWorker();
isDbAvail.WorkerReportsProgress = true;
isDbAvail.DoWork += isOnline;
isDbAvail.ProgressChanged += rewriteOnlineStatus;
isDbAvail.RunWorkerAsync();
}
private void rewriteOnlineStatus(object sender, ProgressChangedEventArgs e)
{
changeStatus((bool)e.UserState);
}
private void isOnline(object sender, DoWorkEventArgs e)
{
while (true)
{
Console.WriteLine("Checking database connection");
Subs.Connection connection = new Subs.Connection();
isDbAvail.ReportProgress(0, connection.isDbAvail);
System.Threading.Thread.Sleep(8000);
}
}
Now the BackgroundWorker is doing the work, and reporting back to the UI thread via ProgressChanged.
Is it possible to add a callback to a background worker while it is running ?
bw.DoWork += new DoWorkEventHandler( some callback );
bw.RunWorkerAsync();
bw.DoWork += new DoWorkEventHandler( some callback );
Thank you.
Yes you can as it's only a subscription to an event but you can't run bw until he has completed the execution of the first task
here an example to illustrate this the following code will show an InvalidOperationException telling This BackgroundWorker is currently busy and cannot run multiple tasks concurrently."
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.RunWorkerAsync();
backgroundWorker1.DoWork+=new DoWorkEventHandler(backgroundWorker2_DoWork);
//at this line you get an InvalidOperationException
backgroundWorker1.RunWorkerAsync();
}
void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
do
{
} while (true);
}
void backgroundWorker2_DoWork(object sender, DoWorkEventArgs e)
{
do
{
} while (true);
}
}
As an answer to your comment question
#SriramSakthivel Thanks. Is there a way to put tasks in a queue ?
yes you can if you are using .net 4.0 you can use task with ContinueWith and attach it to your UI
taskScheduler it will have the same behavior as if you are using BackgroundWorker
private void TestButton_Click(object sender, EventArgs e)
{
TestButton.Enabled = false;
var uiThreadScheduler = TaskScheduler.FromCurrentSynchronizationContext();
var backgroundTask = new Task(() =>
{
Thread.Sleep(5000);
});
var uiTask = backgroundTask.ContinueWith(t =>
{
TestButton.Enabled = true;
}, uiThreadScheduler);
backgroundTask.Start();
}
I have an application which i am add files to my Listbox and run those files.
My application play this files using PcapDot.Net project DLLs and send the packets through the network adapter.
The way is very simple: after all the files added to my application Listbox and the play button clicked the application handle the first file and after this file finished the next file began.
what i want to do is add control to my GUI that control the number of open thread in order to have the ability to play several file simultaneous.
This is my play button event:
private BackgroundWorker bw;
private void btnPlay_Click(object sender, EventArgs e)
{
bw = new BackgroundWorker();
bw.WorkerReportsProgress = true;
bw.WorkerSupportsCancellation = true;
bw.DoWork += new DoWorkEventHandler(bw_DoWork);
bw.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged);
bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
manualResetEvent = new ManualResetEvent(false);
if (bw.IsBusy != true)
bw.RunWorkerAsync();
}
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 0; i < listBoxFiles.Items.Counti++) //run in loop all over my listbox
{
// here if have several wiresharkFile events that update my UI:
wiresharkFile.statusChangedEvent += new WiresharkFile.StatusChangedDelegate(
(wFile) =>
{
bw.ReportProgress(wiresharkFile.packetProgressPrecentage, wiresharkFile);
});
wiresharkFile.sendBuffer(); //play the file
}
}
What is the best way to add option to open more than 1 thread in the same time ?
here is a simple example for your use, it shows how to create and sign to an event you'll pop when the thread that open a file ends and then you can, when the event pop, to open another file. make sure you keep a counter and a lock so you won't have race conditions
public delegate void FileClosedHndlr();
public class MyThread
{
private event FileClosedHndlr FileClosed;
public void MyMain()
{
Thread t = new Thread(new ThreadStart(start));
FileClosed += new FileClosedHndlr(MyThread_FileClosed);
t.Start();
}
void MyThread_FileClosed()
{
// Thread has ended file open
// open another file
}
private void start()
{
// Open the file
// End thread
if (FileClosed != null)
{
FileClosed();
}
}
}
it took me a while, so use it
This case is using C# WPF. I want to instantly disable a button after clicking it to prevent clicking it twice in short succession. I disabled the button in OnClick_Event but still clickable.
Part of source is as below.
private void Button_Click_UpdateBurndownChart(object sender, RoutedEventArgs e)
{
if(threadNotWorking)
{
updateButton.IsEnabled = false;
startWorkThread();
}
}
private void startWorkThread()
{
... ...
//after finish required process
updateButton.IsEnabled = true;
}
Is there any way to accomplish this?
you may want to use a dispatcher, there is probably a threading problem (callback function running on seperate thread and trying to access ui which runs on another thread). try this . .
updateButton.Dispatcher.BeginInvoke(
new ThreadStart(() => updateButton.IsEnabled = false),
System.Windows.Threading.DispatcherPriority.Input, null);
instead of
updateButton.IsEnabled = false;
What happens if you were instead to change the order of your events from:
updateButton.IsEnabled = false;
startWorkThread();
To
startWorkThread();
updateButton.IsEnabled = false;
Let me know how this goes.
What it looks like is that you are starting your thread then immediatly enabling your button before your thread has finished. You would be better off using a BackgroundWorker and enable your Button in the RunWorkerCompleted Event. Though you can do something similar by enabling your button using a BeginInvoke at the end of your Process.
public void doWork()
{
System.Threading.Thread.Sleep(10000); //Simulating your Process
Dispatcher.BeginInvoke(new System.Threading.ThreadStart(delegate() { updateButton.IsEnabled = true; }), System.Windows.Threading.DispatcherPriority.Background);
}
Example with BackgroundWorker
using System.ComponentModel;
public partial class MainWindow : Window
{
BackgroundWorker bgw;
public MainWindow()
{
InitializeComponent();
bgw = new BackgroundWorker();
bgw.DoWork += new DoWorkEventHandler(bgw_DoWork);
bgw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted);
}
void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
updateButton.IsEnabled = true;
}
void bgw_DoWork(object sender, DoWorkEventArgs e)
{
System.Threading.Thread.Sleep(10000); //Simulating your work
}
private void startWorkThread()
{
bgw.RunWorkerAsync();
}
private void updateButton_Click(object sender, RoutedEventArgs e)
{
if (bgw.IsBusy != true)
{
updateButton.IsEnabled = false;
startWorkThread();
}
}
}